Commercial and industrial liquids of all types are stored in underground storage tanks. The capacity of such tanks are at least 1,000 gallons liquid and typically are 10,000 to 20,000 gallons liquid. The tanks presently being sold are made of metal or a fibrous reinforced resinous material. The metal storage tanks are made of a heavy gauge steel and are cylindrical-shaped. The fibrous reinforced resinous material tanks are usually ribbed for added strength.
Regardless of the material used to make the underground storage tanks, the tanks must have sufficient wall strength to withstand internal and external weight forces. Increased wall thickness does increase wall strength, but also increases the cost of producing the tank and difficulty in installing it. Clearly, any leakage from the tanks, whether due to a complete collapse of a small hole can have a substantial impact on the environment of health of nearby residents.
A need for a underground storage tank which can safely hold a substantial amount of potentially dangerous liquid is well recognized. Double walls storage tanks have been suggested. Various new methods of building tanks have also been suggested in recently issued patents. Still more efficient and cheaper methods of making reliable storage tanks are needed. In accord with this continuing need, there has been developed a storage tank with strengthened walls and optionally leak detection capability. The tanks are economically built and are installed with conventionally used equipment.